You could not say that the Father was the God of the Lord Jesus Christ before the incarnation.
When I view the eternal Son as Man, I get the Father of our Lord Jesus Christ, not as with us, sons by adoption, but the Father's only-begotten Son. I was brought into the family by adoption before time was.
My fellowship with the Father is my taste of the delight He has in the Only-begotten.
That Son came into the world as the perfect presentation of all that the Father is; and the Son is presented to me, and all the fullness of God is poured into my heart through Him.